Suburban Air

Does the front have plenty of airflow, but not cold enough? Check the tube that goes from the condenser to the firewall. It should be cold from about 5 inches behind the condenser to the firewall. If it is not, even if it is VERY cold up front, but loses it's coolnear the firewall, check the orifice tube. If it is cold all the way to the firewall, but blows only slightly cool air, check your blend door, it might be blending too much heated air from the heater core. Try MAX A/C when you first start it, does it initially go full tilt cold then warm up with the motor? Since you say the rear A/C works, I would suspect the Orifice tube.

Is it cold enough, but not enough airflow? Check for obstructions in the inlet path up to the face of the evaperator.

KenG

I'll check those things out. It seems to have plenty of air flow, just not cold air. The orface tube was my thought as well, but don't want to open it up for no reason.

Thanks

None of the lines feel that cold at all. The two coming from the condensor to the dryers seem a little cool, but that's it.

I plan >> Recently the front air on my 1999 Suburban doesn't seem to be blowing

Well, I got my gauges and hooked them up. This is what I found...

The compressor cycled on/off for a few minutes with the Low side going up to about 60psi and the High side never went up much past 25psi. Both fluctuated up and down as the compressor cycled, but never went much beyond those levels. Once the compressor stayed going, the low stopped moving and seemed to equalize with the high side.

I checked it again and the whole time they were equalized. 75psi with engine off, 25psi with engine on and compressor on.

What might this be?

The high side pressure can not be lower than the low side pressure, physically impossible. Your gauges weren't hooked to the correct ports, or the gauges are goosed. With the engine off the pressures should equalize between high and low, and the pressure should be about the same as the ambient temperature on a summers day. so if it was 72-78 degrees out, that sounds about right.

Whitelightning

So, with engine off, all sounds about fine?

The gauges can't be hooked up incorrectly, as the fitting(s) won't allow it. I might have had something set wrong, but I was trying to follow the manual that came with the gauges. A paper I have from one of the freon makes says if low side is normal and high side low, then the valves in compressor aren't working correctly. A buddy told me, his understanding is they will make a clicking sound. Mine does make a chatter, which might be described as clicking.

One question I do have is should I open the both valves on gauge itself? Or not? The manual says to do that, but my friend thought that would cause the system to equalize. I'm sure I did it the same both times. One time, the high side definately read lower than the low side, the next they stayed equalized.

I might check it again or wait until I can get to my friends shop. He messes with this stuff more than I do. I'll post any findings.

Thanks for the help!!

"MASTER Brian" .20394$2g4.11048@dukeread09...

The valve on the high side should never ever be opened by an end user, especially when charging the system with then engine running, unless you like explosions and don't like your hand, eyes, or other body parts. Both valves should be shut to check pressures, Both valves open will allow refrigerant to move between the high side and low side, if there is a can on the gauge set, it will allow the high side pressure to hit the can which isn't going to hold the 150psi plus the high side should be showing when running. The pressures should be checked as I said with both valves on the gauges shut off.(the big knobs) if these are legal gauges for 134a there should be little butterfly valves near the connections to the vehicle, these should be open. The blower should be on high, the air set to max or recirculate, and if possible a hefty box fan in front of the grill area to simulate ram air effect. A bad fan clutch can cause false readings.

Please don't take this the wrong way, but if you don't know what you are doing take it to a pro. Normal low side should be about 35psi, low highside would 75-95 psi. If it has rear air, it should be running too. many variables to account for. Refrigerants can burn you, literally, it can blind you. And 134a systems are finicky beasts, 1/4 pound under or over charged and they don't work worth a tinkers damn when its really hot out. When they are right they will cool as good , sometimes better than r-12(there will be argument on this I am sure) meaning you need someone who knows the system, not someone who "messes" with it.

Whitelightning

Thanks for the info. Either the manual I have for these gauges is wrong or I read them incorrectly. I am certain they said to "OPEN" both valves at the gauge. Hmmm....

With that said the gauges are not expensive gauges, but they should be "legal" they were sold as 134a gauges and they do have the valves at the connections as well as the quick connects for the 134a valves. I didn't have a can hooked up, the hose for that was connected back to the gauge manifold. I realize you only want to fill with the low side open and thought it sounded strange to have both valves open for the test, but it's what the manual said. I will also admit, I don't do this enough to remember all, which is why I am here asking, but I also don't consider myself as not knowing, even though I'm not certified. I have been charging my own cars since I was 16 and you could buy R12 off the shelf. My friend was certified when he worked as an AMP for learjet, so I also don't look at him as someone who "messes" with this stuff, though he doesn't do it for a living. He does operate a small dealership and rebuilds hot-rods and charges his own cars when needed. Don't worry, I didnt' take that the wrong way, it's always better safe than sorry.

Oh, and yes this does have rear heat/air. I had both on max and max cool on. I didn't however have a box fan in front of radiator, didn't think about that. I just wanted an idea as to whether I was low on freon or if I had a faulty compressor.

I'll re-check with valves at manifold shut. Thanks again...

I sometimes come across a little gruff, but I've seen too many things I wish I hadn't, or wish could at least forget. 6 years ago was the most recent, I heard a neighbor's wife just screaming, the most ungodly scream you never want to hear. Her husband had been working on his truck in the back yard while she was at work, no jack stands, This was 2 weeks before Christmas, hell of a present, damn glad she got home before the kids got home from school. You can buy a damn set of jack stands for under $20 these days. I've seen batteries blow up because of an idiot smoking while doing a load test. Do you know an oxygen tank really will go though a cinder block wall if the valve is knocked off.. I digress. And why do shop teachers always seem to be missing a finger or two? lol

Whitelightning

I understand fully!